One of the world's wackiest footraces will lurch into action at 8 a.m. on May 15, when the 94th running of the Bay-to-Breakers begins, sending a horde of highly decorated runners hurtling along the 7.46 mile-long course from the San Francisco Embarcadero to the Pacific Ocean shoreline at Golden Gate Park. Early registration, with discounted fees will close at the end of tomorrow (April 15); those fees are, $29.50 (adults) and $24.50 (youth, ages 18 and under). Regular registration, which can be accomplished online (until May 12) or by regular mail (until May 9) costs $34.50 and $29.50. Finally, late registration can only be achieved in person at the Greater Body Expo, May 13-14, for $40 and $35. This Expo takes place 11 a.m.-7 p.m. Friday and 9 a.m.-7 p.m. Saturday at the Bill Graham Civic Auditorium, at 99 Grove St. in San Francisco. It includes exhibits and seminars focused on advances in health and fitness lore; bargains on running shoes and fitness equipment. Race registration and packet pickup will be available both days until 6 p.m. Following the run, the event presents Footstock, a festival and live concert at the Polo Fields in Golden Gate Park, featuring the sounds of Gavin DeGraw, a costume contest, a food marketplace and beer gardens. KGO Newstalk AM 810 will provide live radio coverage, starting at 5 a.m. KRON 4 will provide live TV coverage, 7:30-10 a.m. This Bay-to-Breakers is sponsored by Albertson's, presented by The Examiner, and benefits medical charities. Information: call hotline at (415) 359-2800; check Web site at baytobreakers.com; or e-mail info@baytobreakers.com

Talk to the heron aide

Nancy DeStefanis, who directs the San Francisco Nature Education program at Stow Lake in Golden Gate Park, announces viewing opportunities for adult herons and their new chicks in nests located around the lake. A heron watch with spotting scopes and commentary by naturalists will be available there, 10 a.m.-1 p.m. on Saturdays until May 21. Special guided walks begin at 10:30 a.m. In addition, two-hour birding classes specially designed for kids will take place at 10 a.m. on May 7 and June 4. Also, DeStefanis herself gives a lecture 7:30-9 p.m. tonight (April 14), at the Randall Museum, 1999 Museum Way in San Francisco (www.randallmuseum.org), "When Birds Were Hats," which details the political empowerment of the early conservation movement. All these activities are free, but donations to the programs are accepted. (415) 387-9160, or www.sfnature.org

Walk to wildflowers in Coe

Bay Nature magazine presents a hike in Northern California's biggest state park, Henry W. Coe (east of Morgan Hill), 10 a.m.-2 p.m. on Sunday (April 17). The four mile probe into the sprawling park's 90,000 hilly acres will be lead by botanist Winslow Briggs, and focus on this spring's great wildflower displays. Participants should meet at the park's visitor center, at the end of East Dunne Avenue. Walk is free, no reservations required. www.coepark.org/directions.html

Same-day ski on water, snow

Alpine Meadows ski resort will hold its 9th annual Ski Nautique Gates & Wakes Fun Day and Pro Challenge, starting at 8 a.m. on April 30. This event lets participants compete in skiing or snowboarding in the morning, then switch over to wakeboarding or waterskiing on Lake Tahoe in the afternoon. The event includes a Disabled Challenge division. Entry: $56 (general), or $46 (children age 12 or younger). Add the Two-Round Slalom waterski on Friday, April 29, and entry is $67 for both days. Information and registration: Bob Bense, (916) 638-3382; or Alpine Meadows at (530) 581-8321 and www.skialpine.com.

Life can be a beach

Another Earth Day offering is a Coastwalk hike and beach clean-up, starting at 10 a.m., April 23, at Goat Rock Beach, at the mouth of the Russian River in Sonoma County. After a short volunteer work party, participants will enjoy a short wildflower and tidepool walk along the Kortum Trail to Shell Beach. Bring a packed lunch, water bottles, layered clothing and good walking shoes. By the way, Coastwalk is the outfit that focuses on finishing the California Coastal Trail, and presents an annual series of excellent guided hikes along the route, from the Oregon border to San Diego. For example, on August 25-29, Coastwalk guides will hit the Marin County portion, offering inspirational visits to redwood groves, scenic shoreline bluffs and the Point Bonita lighthouse. Hikes include arranged lodging and fantastic meals; participants only carry a daypack. For Earth Day, contact Willow at (707) 829-6689. For full Coastwalk agenda: (800) 550-6854, ext. 5, or www.coastwalk.org